Respiratory syncytial virus (RSV) is the most important cause of respiratory tract illness especially in young infants that develop severe disease requiring hospitalization, and accounting for 74,000-126,000 admissions in the United States (Rezaee et al., 2017; Resch, 2017). Observations of neonatal and infant T cells suggest that they may express different immune markers compared to T-cells from older children. Flow cytometry analysis of cellular responses using "conventional" anti-viral markers (IL2, IFN-γ, TNF, IL10 and IL4) upon RSV-peptide stimulation detected an overall low RSV response in peripheral blood. Therefore we sought an unbiased approach to identify RSV-specific immune markers using RNA-sequencing upon stimulation of infant PBMCs with overlapping peptides representing RSV antigens. To understand the cellular response using transcriptional signatures, transcription factors and cell-type specific signatures were used to investigate breadth of response across peptides. Unexpected from the ICS data, M peptide induced a response equivalent to the F-peptide and was characterized by activation of GATA2, 3, STAT3 and IRF1. This along with upregulation of several unconventional T cell signatures was only observed upon M-peptide stimulation. Moreover, signatures of natural RSV infections were identified from the data available in the public domain to investigate similarities between transcriptional signatures from PBMCs and upon peptide stimulation. This analysis also suggested activation of T cell response upon M-peptide stimulation. Hence, based on transcriptional response, markers were chosen to validate the role of M-peptide in activation of T cells. Indeed, CD4+CXCL9+ cells were identified upon M-peptide stimulation by flow cytometry. Future work using additional markers identified in this study could reveal additional unconventional T cells responding to RSV infections in infants. In conclusion, T cell responses to RSV in infants may not follow the canonical Th1/Th2 patterns of effector responses but include additional functions that may be unique to the neonatal period and correlate with clinical outcomes.

Keywords: PBMC; Peptide stimulation; RSV; Transcriptomics.

Recent studies using in vivo models have characterized lymph flow and demonstrated that lymph flow plays a key role in the later stages of lymphatic vascular development, including vascular remodeling, to create a hierarchical collecting vessel network and lymphatic valves (Sweet et al., J Clin Invest 125, 2995-3007, 2015). However, mechanistic insights into the response of lymphatic endothelial cells to fluid flow are difficult to obtain from in vivo studies because of the small size of lymphatic vessels and the technical challenge of lymphatic endothelial cell isolation. On the other hand, in vitro experiments can be tailored to isolate and test specific mechanotransduction pathways more cleanly than conditions in vivo. To measure in vitro the cellular response to flow, cultured primary lymphatic endothelial cells can be exposed to highly specific fluid forces like those believed to exist in vivo. Such in vitro studies have recently helped identify FOXC2 and GATA2 as important transcriptional regulators of lymphatic function during valve formation that are regulated by lymph flow dynamics. This chapter discusses the methods used to expose primary lymphatic endothelial cells (LECs) to lymph fluid dynamics and the relationship of these in vitro studies to in vivo lymphatic biology.

In this issue of Blood, Wlodarski and colleagues demonstrate that as many as 72% of adolescents diagnosed with myelodysplastic syndrome (MDS) and monosomy 7 harbor germline mutations in GATA2. Although pediatric MDS is a very rare diagnosis, occurring in 0.8 to 4 cases per million, Wlodarski et al screened >600 cases of primary or secondary MDS in children and adolescents who were enrolled in the European Working Group on MDS consortium over a period of 15 years. The overall frequency of germline GATA2 mutations in children with primary MDS was 7%, and 15% in those presenting with advanced disease. Notably, mutations in GATA2 were absent in patients with therapy-related MDS or acquired aplastic anemia.

Hundreds of sterile alpha motif (SAM) domains have predicted structural similarities and are reported to bind proteins, lipids, or RNAs. However, the majority of these domains have not been analyzed functionally. Previously, we demonstrated that a SAM domain-containing protein, SAMD14, promotes SCF/proto-oncogene c-Kit (c-Kit) signaling, erythroid progenitor function, and erythrocyte regeneration. Deletion of a Samd14 enhancer (Samd14-Enh), occupied by GATA2 and SCL/TAL1 transcription factors, reduces SAMD14 expression in bone marrow and spleen and is lethal in a hemolytic anemia mouse model. To rigorously establish whether Samd14-Enh deletion reduces anemia-dependent c-Kit signaling by lowering SAMD14 levels, we developed a genetic rescue assay in murine Samd14-Enh^-/- primary erythroid precursor cells. SAMD14 expression at endogenous levels rescued c-Kit signaling. The conserved SAM domain was required for SAMD14 to increase colony-forming activity, c-Kit signaling, and progenitor survival. To elucidate the molecular determinants of SAM domain function in SAMD14, we substituted its SAM domain with distinct SAM domains predicted to be structurally similar. The chimeras were less effective than SAMD14 itself in rescuing signaling, survival, and colony-forming activities. Thus, the SAMD14 SAM domain has attributes that are distinct from other SAM domains and underlie SAMD14 function as a regulator of cellular signaling and erythrocyte regeneration.

Rapid morphological and gene expression changes occur during the early formation of a mammalian blastocyst. Critical to successful retention of the blastocyst and pregnancy is a functional trophectoderm (TE) that supplies the developing embryo with paracrine factors and hormones. The contribution of TE conformational changes to gene expression was examined in equine induced trophoblast (iTr) cells. Equine iTr cells were cultured as monolayers or in suspension to form spheres. The spheres are hollow and structurally reminiscent of native equine blastocysts. Total RNA was isolated from iTr monolayers and spheres and analyzed by RNA sequencing. An average of 32.2 and 31million aligned reads were analyzed for the spheres and monolayers, respectively. Forty-four genes were unique to monolayers and 45 genes were expressed only in spheres. Conformation did not affect expression of CDX2, POU5F1, TEAD4, ETS2, ELF3, GATA2 or TFAP2A, the core gene network of native TE. Bioinformatic analysis was used to identify classes of genes differentially expressed in response to changes in tissue shape. In both iTr spheres and monolayers, the majority of the differentially expressed genes were associated with binding activity in cellular, developmental and metabolic processes. Inherent to protein:protein interactions, several receptor-ligand families were identified in iTr cells with enrichment of genes coding for PI3-kinase and MAPK signaling intermediates. Our results provide evidence for ligand initiated kinase signaling pathways that underlie early trophectoderm structural changes.

Erythroid progenitors that respond to erythropoietin (Epo) are present in the liver of adult Xenopus laevis. However, cells responding to Epo in the larval liver and through the metamorphosis period under hepatic remodeling have not been characterized. In this study, tadpoles were staged using the tables of Nieuwkoop and Faber (NF). Liver cells from pre- (NF56) or post- (NF66) metamorphic stage were cultured in the presence of Epo. β2-globin mRNA expression peaked at day 7 after the start of culture. Larval β2-globin was highly expressed in NF56-derived cells, while adult β2-globinwas detected in those of NF66. In both NF56- and NF66-derived cells, mRNA expression of eporand gata2 peaked at day 5 and days 3-4, respectively. In contrast, gata1 expression peaked at day 6 in NF56 cells and at day 5 in NF66 cells. Half maximal proliferation of erythrocytic blast cells derived from the liver at NF66 was observed at day 3, which was earlier than that of NF56. These results indicate that erythroid progenitors that respond to Xenopus laevis Epo are maintained in pre- and post-metamorphic liver, although the tissue architecture changes dramatically during metamorphosis. Additionally, the globin switching occurred, and/or the erythroid progenitors for larval erythrocytes were replaced by those for adult erythrocytes in the metamorphic liver.

Among the potential larval shell formation genes in mollusks, most are expressed in cells surrounding the shell field during the early phase of shell formation. The only exception (cgi-tyr1) is expressed in the whole larval mantle and thus represents a novel type of expression pattern. This study reports another gene with such an expression pattern. The gene encoded a SoxC homolog of the Pacific oyster Crassostrea gigas and was named cgi-soxc. Whole-mount in situ hybridization revealed that the gene was highly expressed in the whole larval mantle of early larvae. Based on its spatiotemporal expression, cgi-soxc is hypothesized to be involved in periostracum biogenesis, biomineralization, and regulation of cell proliferation. Furthermore, we investigated the interrelationship between cgi-soxc expression and two additional potential shell formation genes, cgi-tyr1 and cgi-gata2/3. The results confirmed co-expression of the three genes in the larval mantle of early D-veliger. Nevertheless, cgi-gata2/3 was only expressed in the mantle edge, and the other two genes were expressed in all mantle cells. Based on the spatial expression patterns of the three genes, two cell groups were identified from the larval mantle (tyr1 +/soxc +/gata2/3 + cells and tyr1 +/soxc +/gata2/3 - cells) and are important to study the differentiation and function of this tissue. The results of this study enrich our knowledge on the structure and function of larval mantle and provide important information to understand the molecular mechanisms of larval shell formation.

Short structural variants-variants other than single nucleotide polymorphisms-are hypothesized to contribute to many complex diseases, possibly by modulating gene expression. However, the molecular mechanisms by which noncoding short structural variants exert their effects on gene regulation have not been discovered. Here, we study simple sequence repeats (SSRs), a common class of short structural variants. Previously, we showed that repetitive sequences can directly influence the binding of transcription factors to their proximate recognition sites, a mechanism we termed non-consensus binding. In this study, we focus on the SSR termed Rep1, which was associated with Parkinson's disease (PD) and has been implicated in the cis-regulation of the PD-risk SNCA gene. We show that Rep1 acts via the non-consensus binding mechanism to affect the binding of transcription factors from the GATA and ELK families to their specific sites located right next to the Rep1 repeat. Next, we performed an expression analysis to further our understanding regarding the GATA and ELK family members that are potentially relevant for SNCA transcriptional regulation in health and disease. Our analysis indicates a potential role for GATA2, consistent with previous reports. Our study proposes non-consensus transcription factor binding as a potential mechanism through which noncoding repeat variants could exert their pathogenic effects by regulating gene expression.

The GATA family of DNA binding proteins consists of six different transcription factors (GATA1-6), each with diverse biologic function. The GATA2 protein has been shown to be vital for proliferation and maintenance of hematopoietic stem cells; mutations result in variable phenotypes including myelodysplastic syndrome.

In the early fetal liver, hematopoietic progenitors expand and mature together with hepatoblasts, the liver progenitors of hepatocytes and cholangiocytes. Previous analyses of human fetal livers indicated that both progenitors support each other's lineage maturation and curiously share some cell surface markers including CD34 and CD133. Using the human embryonic stem cell (hESC) system, we demonstrate that virtually all hESC-derived hepatoblast-like cells (Hep cells) transition through a progenitor stage expressing CD34 and CD133 as well as GATA2, an additional hematopoietic marker that has not previously been associated with human hepatoblast development. Dynamic expression patterns for CD34, CD133, and GATA2 in hepatoblasts were validated in human fetal livers collected from the first and second trimesters of gestation. Knockdown experiments demonstrate that each gene also functions to regulate hepatic fate mostly in a cell-autonomous fashion, revealing unprecedented roles of fetal hematopoietic progenitor markers in human liver progenitors.

We report a male with longstanding warts who presented with severe West Nile virus encephalitis (WNVE) and recovered after interferon alfa-2b and intravenous immunoglobulin. He was later found to have GATA2 deficiency and underwent successful hematopoietic stem cell transplant.

The transcription factor (TF) GATA2 plays a key role in organ development and cell fate control in the central nervous, urogenital, respiratory, and reproductive systems, and in primitive and definitive hematopoiesis. Here, we generate a knockin protein reporter mouse line expressing a GATA2VENUS fusion from the endogenous Gata2 genomic locus, with correct expression and localization of GATA2VENUS in different organs. GATA2VENUS expression is heterogeneous in different hematopoietic stem and progenitor cell populations (HSPCs), identifies functionally distinct subsets, and suggests a novel monocyte and mast cell lineage bifurcation point. GATA2 levels further correlate with proliferation and lineage outcome of hematopoietic progenitors. The GATA2VENUS mouse line improves the identification of specific live cell types during embryonic and adult development and will be crucial for analyzing GATA2 protein dynamics in TF networks.

Keywords: GATA2; cell fate; development; fluorescent protein; hematopoietic stem and progenitor cell; monocyte and mast cell lineage; transcription factor networks; transgenic mouse.

During embryonic development, hematopoietic cells are present in areas of blood-vessel differentiation. These hematopoietic cells emerge from a specific subpopulation of endothelial cells called the hemogenic endothelium. We have previously found that mouse proepicardium contained its own population of endothelial cells forming a network of vascular tubules. We hypothesize that this EC population contains cells of hematopoietic potential. Therefore, we investigated an in vitro hematopoietic potential of proepicardial cell populations. The CD31+/CD45-/CD71- cell population cultured for 10 days in MethocultTM gave numerous colonies of CFU-GEMM, CFU-GM, and CFU-E type. These colonies consisted of various cell types. Flk-1+/CD31-/CD45-/CD71-, and CD45+ and/or CD71+ cell populations produced CFU-GEMM and CFU-GM, or CFU-GM and CFU-E colonies, respectively. Immunohistochemical evaluations of smears prepared from colonies revealed the presence of cells of different hematopoietic lineages. These cells were characterized by labeling with various combinations of antibodies directed against CD31, CD41, CD71, c-kit, Mpl, Fli1, Gata-2, and Zeb1 markers. Furthermore, we found that proepicardium-specific marker WT1 co-localized with Runx1 and Zeb1 and that single endothelial cells bearing CD31 molecule expressed Runx1 in the proepicardial area of embryonic tissue sections. We have shown that cells of endothelial and/or hematopoietic phenotypes isolated from mouse proepicardium possess hematopoietic potential in vitro and in situ. These results are supported by RT-PCR analyses of proepicardial extract, which revealed the expression of mRNA for crucial regulatory factors for hemogenic endothelium specification, i.e., Runx1, Notch1, Gata2, and Sox17. Our data are in line with previous observation on hemangioblast derivation from the quail PE.

iASPP can prompt the cell proliferation and inhibit the apoptosis of many cells. There are putative binding sites of transcription factor GATA-2 upstream of iASPP transcription start site. GATA-2 plays an important role in the proliferation and differentiation of hematopoietic stem cells (HSC) and progenitors. This study was aimed to explore the role of GATA-2 protein in iASPP gene transcription. Firstly, the expression of iASPP and GATA-2 protein in some leukemia cell lines was detected by Western blot. Second, The expressive vector of pCMV5-GATA2 and the luciferase reporter vectors containing possible binding sites of GATA-2 were constructed and co-transfected into HEK293 and CV-1 cells. Then the luciferase activity was assayed by luminometer. Also, ChIP assays were performed to further confirm the specific binding of GATA-2 to iASPP promoter. The results showed that GATA-2 was overexpressed in most cell lines with high level of iASPP. GATA-2 exhibited a significant effect on luciferase activity of reporter gene iASPP and in a dose-dependant manner. The relative luciferase activity was up-regulated to about two-fold of the empty vector control when the transfection dose of pCMV5-GATA2 plasmid was increased to 100 ng. While the effect was more significant in CV-1 cells and showed a 6.7-fold increase. The ChIP assay demonstrated the in vivo specific binding of GATA-2 to iASPP. The binding sites of GATA2 were located between nt -361 ∼ -334 in upstream of iASPP gene transcription start site. It is concluded that transcription factor GATA-2 can bind with the cis-regulatory region of the iASPP promoter and up-regulate iASPP expression.

Purpose: To characterize rheumatological manifestations of GATA2 deficiency.

Methods: Single-center, retrospective review of 157 patients with GATA2 deficiency. Disease course, laboratory results, and imaging findings were extracted. In-person rheumatological assessments were performed on selected, available patients. A literature search of four databases was conducted to identify additional cases.

Results: Rheumatological findings were identified in 28 patients, out of 157 cases reviewed (17.8%). Twenty-two of those patients (78.6%) reported symptom onset prior to or in conjunction with the molecular diagnosis of GATA2 deficiency. Notable rheumatological manifestations included: piezogenic pedal papules (PPP), joint hyperextensibility, early onset osteoarthritis, ankylosing spondylitis, and seronegative erosive rheumatoid arthritis. In peripheral blood of patients with rheumatological manifestations and GATA2 deficiency, CD4+ CD3+ helper T cells and naïve CD3+ CD4+ CD62L+ CD45RA+ helper T cell subpopulation fractions were significantly lower, while CD8+ cytotoxic T cell fractions were significantly higher, compared to those without rheumatological manifestations and with GATA2 deficiency. No changes in CD19, CD3, or NK populations were observed.

Conclusion: GATA2 deficiency is associated with a broad spectrum of rheumatological disease manifestations. Low total helper T lymphocyte proportions and low naïve helper T cell proportions are associated with those most at risk of overt rheumatological manifestations. Further, PPP and joint hyperextensibility may explain some of the nonimmunologically-mediated joint problems encountered in patients with GATA2 deficiency. This catalogue suggests that rheumatological manifestations and immune dysregulation are relatively common in GATA2 deficiency.

BACKGROUND

Autosomal dominant haploinsufficiency of GATA2 causes monocytopenia and natural killer cell lymphopenia, resulting in predisposition to mycobacterial, fungal, and viral infections.

METHODS

Herein we report on the clinical, serologic, electrophysiologic, and pathologic evaluations of a 29-year-old woman with GATA2 haploinsufficiency and active Epstein-Barr virus (EBV) infection complicated by subacute painful neuropathy.

RESULTS

Nerve conduction and electromyography studies showed predominantly demyelinating sensorimotor polyradiculoneuropathy. Lumbar spine MRI showed thickening and enhancement of the cauda equina nerve roots. Serum and cerebrospinal fluid anti-IgG and IgM EBV capsid and nucleic acid antibodies were positive. Sural nerve biopsy showed microvasculitis and an increased frequency of fibers with segmental demyelination. Intravenous immunoglobulin and steroids improved the patient's neuropathy.

CONCLUSIONS

GATA2 mutation-related immunodeficiency may predispose to EBV-associated subacute demyelinating polyradiculoneuropathy by both viral susceptibility and immune dysregulation. In patients who present in this manner, immunodeficiency syndromes should be considered when lymphomatous infiltration is excluded. Immunotherapy can be helpful. Muscle Nerve 57: 150-156, 2018.

OBJECTIVE

To examine the association between GATA2 deficiency-related myelodysplastic syndrome (MDS) and central retinal vein occlusion (CRVO).

METHODS

Clinical ophthalmologic examination and laboratory work-up was performed for a patient with GATA2 deficiency-related MDS who experienced a unilateral CRVO. The literature was reviewed for reports of CRVO in the setting of MDS and allogeneic hematopoietic stem cell transplantation.

RESULTS

Ophthalmologic examination revealed findings consistent with unilateral CRVO. Typical hypercoagulable work-up did not reveal an identifiable cause. A review of the patient's medical history revealed multiple potential causes of CRVO, including drug-induced and/or related to her history of MDS and hematopoietic stem cell transplantation. The literature was reviewed for reports of CRVO in association with her risk factors.

CONCLUSIONS

On review of the literature, we determined that GATA2 deficiency-related MDS was a possible cause of this patient's CRVO although it is likely that her multiple risk factors worked synergistically to create a prothrombotic state. This case and review of the literature serve as an important reminder of the long and ever-evolving list of risk factors for the development of CRVO.